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CDM-600 Satellite Modem Revision 7
Clock Modes and Drop and Insert (D&I) MN/CDM600.IOM
10–10
10.8 Rx Buffer Clock = Insert (D&I only)
The E1 or T1 clock recovery from the IDI G.703 port serves as the Rx Buffer reference.
In addition, the recovered data is the E1/T1 input to the Insert Mux. If the Rx G.703
recovery circuit detects no activity at IDI input, or cannot detect the expected frame
format, Buffer Clock = Rx Satellite will be chosen as a fall-back.
If ‘Insert’ is not the selected buffer clock reference, the clock and data from the IDI port
is ignored, and a new E1/T1 frame is generated. The time slots coming from the satellite
are then re-inserted into the selected timeslots of this new blank frame, and output on the
IDO port.
10.9 Single-Source Multiple Modems
Two ways to connect a single T1 or E1 stream to several modems are by looming or
daisy-chaining modems. Each method is illustrated in Figure 10-5 for Looming and
Figure 10-6 for daisy chain and each requires the RX Buffer Clock = Insert setting.
• Assign all timeslots to not overlap.
• Assign modems to number of TX/RX channels as required.
BIT ERROR TEST
IDO(RX)
IDI(LOOP)
DDO(LOOP)
DDI(TX)
IDO(RX)
IDO(RX)
IDI(LOOP)
IDI(LOOP)
DDO(LOOP)
DDO(LOOP)
DDI(TX)
DDI(TX)
Figure 10-5. Single-Source Multiple Modems (Looming)
- - - - - - - - - - Receive
_
__________ Transmit